Mechanics | Relativity Answers

when hit, the velocity of a 0.2 kg baseball changes from +25m/s to -25m/s. what is the magnitude of the impulse delivered by the bat to the ball?

using method of integration, show that the moment of inertia of a uniform thin rod of length L about an axis perpendicular to the rod at a point L/4 from one of its ends can be written as 7/48ML2

A system of pulley has a velocity ratio of 15 and AMA of 8.Find

1. the effort

2. the work output

3. the work input

4. the efficiency

A ball is thrown forward vertically from the top of a cliff with a velocity of 10m/s.The height of the cliff above the ground is 45m.Calculate the time to reach the ground,the distance from the cliff of the ball on hitting the ground,the direction of the ball to the horizontal just before it hits the ground

1. What is the power of a 50kg woman in climbing a hill 500m high?
2. How long will a 42kg girl with an average power of 30watts run up a staircase to the second floor of a building 6m high?
3. A sack of cement with a mass of 120kg is lifted by a construction worker in 15m from the ground. Compute the amount of work done by the construction worker and his power after accomplishing the work in 30 minutes?

1.   Calculate the kinetic energy and momentum of a proton traveling 2.90 𝑥 108 𝑚/𝑠.

1.   A box at rest has the shape of a cube 2.6 m on a side. This box is loaded onto the flat floor of a spaceship and the spaceship then flies past us with a horizontal speed of 0.80c. What is the volume of the box as we observe it?

determine the precision of these two approximate values:

a) 3000. ft

b) 1.20 times 10^(--5)ms

^{be careful, first write in std.dec.form}

Calculate the rotational inertia of a meter stick, with mass 0.24 kg, about an axis perpendicular to the stick and located at the 30 cm mark. (Treat the stick as a third rod.)

a) 90.7 x 10^-3 kg.m²

b) 41.6 x 10^-3 kg.m²

c) 20 x 10^-3 kg.m²

d) 29.6 x 10^-3 kg.m²

An aeroplane starting to fliy 300km at point A ,then 250 km at 30°west of north,the 150 km north to arrive at B . Calculate the vector position in each displacement in unit vector notation